Qualified dividends (and capital gains) are taxed at a lower rate than ordinary income. In fact, the lowest bracket of qualified dividends is taxed at 0% in these income ranges.
$0-$38,600 - Single
$0-$77,200 - Married Filing Jointly
$0-$51,700 - Head of Household
$0-$38,600 - Married Filing Separately
So I would not be surprised if qualified dividends were excluded from your estimated tax for 2019, depending on your income.